1. Field of the invention
Conventional evaporative cooling towers are of the cross-flow or counter-flow type. The counter-flow type employs a heat exchanger section consisting of spray nozzles, fill material, and a rain zone as the droplets fall to the basin below. Counter-flow fill material is generally of the film type. The air is drawn from below the fill and passes in a direction counter to the general direction of the water flow. Cross-flow type cooling towers employ a heat exchange section to the outside of the central plenum through which the air discharges. Cross-flow fills are generally of the splash type in which the water is broken into small droplets as it falls through the fill material. The air passes through these droplets in a direction generally normal to the direction of water flow. In the case of mechanical draft cooling towers, a positive air flow is created by large fans. The air flow in natural draft cooling towers is induced by the high chimney or veil constructed above the heat exchanger section of the cooling tower.
The art of evaporative cooling is-quite ancient, but only relatively recently has it been studied scientifically. The first hyperbolic natural draft cooling towers were constructed at the Emma Pit in the Netherlands in about 1915. However, the first successful analysis of heat transfer was not formulated until about 1926 by Merkle. Thermal performance remained largely proprietary until the publication of Kelly's Handbook of Crossflow Performance Curves by Neil W. Kelly in 1976l. Most recently, the thermal performance of cooling towers may be predicted by employing computer programs such as the Cooling Tower Adviser published by The Electric Power Research Institute, and the Fast Analysis Cooling Tower Simulator which was developed by Dr. Dudley J. Benton of the Tennessee Valley Authority.
2. Description of the Prior Art
Cooling towers have been devised and disclosed which utilize sprays interior to the tower. Examples of such designs are those disclosed in U.S. Pat. Nos. 1,586,083 to Greene, V Lewis, 3,360,906 to Parkinson, and in Austrian Pat. No. 198,209 to Wasser. In these designs, the traditional fill material is replaced with water sprays. The orienting of the sprays in the direction of the desired air flow was said to increase the velocity of the entering air. The spraying system disclosed in U.S. Pat. No. 1,686,632 to Edge was proposed to promote air flow either with or without a cooling tower. The design for a cooling basin was disclosed in U.S. Pat. No. 2,591,100 to Rouse. In this design a portion of the water to be cooled is pumped under pressure through riser pipes and sprayed through slots designed to produce a spray directed towards the center of the basin. A similar design was disclosed in U.S. Pat. No. 3,983,192 to Stoker in which the water is sprayed through nozzles which are arranged to minimize the interaction of the water droplets from the nozzles.